84 BULIMULUS-PROTOGLYPTUS. 



admitted that rigid diagnoses are impossible, so great is the range 

 variation within each of the three. The rank of subgenera is, there- 

 fore, nominal. 



I. PROTOGLYPTUS (p. 84). Eastern and northern South Amer- 

 ica, Trinidad, etc. 



II. N^ESIOTUS (p. 94). Galapagos Islands. 



III. ORTHOTOMIUM (p. 125). Central and northern Mexico, Lower 

 California, southern United States. 



Subgenus PROTOGLYPTUS Pilsbry, 1897. 



Bulimuli with the apical whorls vertically costulate, the shell 

 ovate-conic, usually rather thin and brownish, the outer lip unex- 

 panded, columella foldless, the columellar lip dilated and reflexed. 



Distribution : eastern South America, Trinidad and some of the 

 Caribbean Islands. 



This group stands somewhat intermediate in conchological char- 

 acters between the typical Bulimulus (with Leptomerus), Rhinus, 

 Orthotomium and Ncesiotus, with certain features not unlike Neo- 

 petrceus. It may be regarded as a surviving primitive type, not 

 much modified from the parent stock of the groups named above. 

 Typical Bulimulus and Scutalus have apparently been differentiated 

 from Protoglyptus by the crinkling of the riblets of the nepionic 

 shell ; Neopetrceus by the development of a system of spirals between 

 the straight riblets, a process culminating in Drymceus. Ncesiotus 

 and Orthotomium are identical with Protoglyptus in apical sculpture, 

 and have both been directly dirived, apparently, from this stock. 



Key to species. 



I. Shell thin, brown or corneous. 



a. Unicolored ; whorls 7 or less ; form ovate or conic. 



b. Densely pilose ; whorls very convex ; aperture 

 decidedly less than half the alt.; alt. 13-14 

 mill. ; whorls 6, pilosus, p. 85. 



b'. With faint spiral stride but no hairs ; dark red- 

 dish-chestnut ; aperture decidedly less than half 

 of alt. Alt. 18-22 mill., chrysaloides, p. 87. 

 b". Pilose when fresh ; whorls 7, convex, sutures 

 deep ; a faint paler peripheral zone ; aperture 

 two-fifths the alt. Alt. 21 mill., 



sanctceludce, p. 86. 



